Subnetting Made Easy

Okay, folks, here is my very short document on Subnetting Made Easy. You should be able to understand and use this document to convince those that you are an expert! (This is the same document I use to teach Networking and Subnetting)
Enjoy!
Jerry

Hello,
I do not see an attachment or a URL link.
PLEASE, resend...
Â
Â
Â
Â
Thank you,

Inquire_98

"This e-mail and any files transmitted with it are intended solely for the use of the individual or entity to which they are addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you have received this e-mail in error, please contact the sender and delete the material from your computer. Please note that any view or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of Primes. ("Primes") and/or its subsidiaries. Finally, the recipient should check this e-mail and any attachments for the presence of viruses. Primes accepts no liability for any damage caused by any virus transmitted by this e-mail."

To annotate with the CIDR Notation, you simply add up the total number of ones in the Subnet Mask. Look at the above table and you will notice that the CIDR Notation equals the number of ones in the Subnet mask. Easy enough!

I believe you made a slight calculation error on Example 1
255.255.224.0 in binary should be
11111111.11111111.11100000.00000000
which gives you 3 1's in the third octet
giving you 2 to the 3rd or 8 so you would have
8 networks. And 13 0's or 2 to the 13th or 8192 - 2
giving you 8190 useable address.

First part is absolutely correct. Actually the first boundary (all 0's) was used for broadcast in the ancient internet days, the second boundary (all 1's) is the current broadcast address.
The broadcast address is used by programs all the time, Microsoft in particular loves to broadcast (at least they used to), just sniff your local subnet to see how much of this crap goes on. There's something the program needs to do to enable this.
Double extra credit, there's a time when a host assigns itself the broadcast address, when is that?

Good answer. You got the double extra credit with that one ;-) When a host comes up that needs to acquire its IP address via DHCP or bootp, it sends a broadcast request to try to find the DHCP or bootp server. Since the DHCP server doesn't have to be on the local subnet the request needs to be an IP packet so it can cross subnet boundaries. Since the DHCP client doesn't have an IP address yet and it needs to be able to receive the reply from the server, and it just can't make up its own address it assumes the internet broadcast address of 255.255.255.255, this way it is guaranteed to see any reply that makes its way back to the DHCP client's subnet. This is one reason why bootp forwarding needs to be enabled on gateways that will be forwarding DHCP traffic because packets destined for 255.255.255.255 aren't normally routed (there's another more subtle reason).
Applications that wish to send a packet to the broadcast IP need to set the socket option SO_BROADCAST. Failure to do say may cause the stack to return EACCES. Note that broadcasts IPs aren't limited to 255.255.255.255. For example, to send a broadcast to all hosts on the Net/24 subnet 192.168.1.0 subnet the broadcast address is 192.168.1.255, for Net/16 subnet 192.168.0.0 it's 192.168.255.255.

I believe that if you use, /23, your subnet mask should be 23 ones, and 9 zeros, or
11111111.11111111.11111110.00000000 resulting in 255.255.254.0 with 512 hosts per subnet.
You used, 11111111.11111111.11111111.11111110 which gives you 128 Networks, with 1 host on each. Not what you want.
So for 10.24.150.0 would extend to 10.24.151.255. You just put 254 in the wrong octet.